<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8">
        <title></title>
        <script src="../vue.js" type="text/javascript" charset="utf-8"></script>
    </head>
    <body>
        <div id="app">
            <p>
                Ask a yes/no question:
                <input v-model="question">
            </p>
            <p>{{ answer }}</p>
        </div>
        <script src="https://cdn.jsdelivr.net/npm/axios@0.12.0/dist/axios.min.js"></script>
        <script src="https://cdn.jsdelivr.net/npm/lodash@4.13.1/lodash.min.js"></script>
        <script type="text/javascript">
            var app = new Vue({
                el: '#app',
                data: {
                    question: '',
                    answer: 'I cannot give you an answer until you ask a question!'
                },
                watch: {
                    // 如果 `question` 发生改变，这个函数就会运行
                    question: function (newQuestion, oldQuestion) {
                        this.answer = 'Waiting for you to stop typing...'
                        this.debouncedGetAnswer()
                    }
                },
                created: function () {
                    // `_.debounce` 是一个通过 Lodash 限制操作频率的函数。
                    // 在这个例子中，我们希望限制访问 yesno.wtf/api 的频率
                    // AJAX 请求直到用户输入完毕才会发出。想要了解更多关于
                    // `_.debounce` 函数 (及其近亲 `_.throttle`) 的知识，
                    // 请参考：https://lodash.com/docs#debounce
                    this.debouncedGetAnswer = _.debounce(this.getAnswer, 500)
                },
                methods: {
                    getAnswer: function () {
                    if (this.question.indexOf('?') === -1) {
                        this.answer = 'Questions usually contain a question mark. ;-)'
                        return
                    }
                    this.answer = 'Thinking...'
                    var vm = this
                    axios.get('https://yesno.wtf/api')
                        .then(function (response) {
                            vm.answer = _.capitalize(response.data.answer)
                        })
                        .catch(function (error) {
                            vm.answer = 'Error! Could not reach the API. ' + error
                        })
                    }
                }
            })
        </script>
        <style type="text/css">
        </style>
    </body>
</html>